The present invention relates to a drive device.
In recent years, various electric vehicles and hybrid vehicles have been developed due to environmental concerns, decrease in crude oil reserves, and the like. For example, a known drive device for a hybrid vehicle has an input shaft connected to an engine, a rotating electrical machine, a planetary gear unit, and an output member, which are arranged coaxially. In such a drive device, one of the coaxially positioned components is preferably positioned so as to axially overlap another component in order to reduce the axial dimension of the drive device and thus reduce the overall size of the drive device.
Japanese Patent Application Publication No. JP-A-2006-262553 (FIG. 2, and the like) describes a vehicle drive device in which ring gears of two planetary gear units are provided integrally with an output member, and the two planetary gear units are positioned radially inside the output member so as to axially overlap the output member. By using this structure, the overall axial dimension of the drive device can be reduced as compared to the case where the two planetary gear units and the output member are sequentially arranged along the axial direction. Regarding the support structure of a rotor shaft of a rotating electrical machine in this vehicle drive device, the rotor shaft is rotatably supported by a case through a bearing on both axial sides. By using this structure, high axial center accuracy of the rotor shaft can be maintained, and an appropriate clearance between a rotor and a stator of the rotating electrical machine can always be ensured. As a result, the generation of vibration and noise due to rotation of the rotating electrical machine can be suppressed.
Japanese Patent Application Publication No. JP-A-H6-328950 (Paragraph [0055], FIG. 6, and the like) describes a vehicle drive device in which a planetary gear unit is positioned radially inside a rotating electrical machine so as to axially overlap the rotating electrical machine. By using this structure, the overall axial dimension of the drive device can be reduced as compared to the case where the rotating electrical machine and the planetary gear unit are sequentially arranged along the axial direction.